This invention relates to foundation units, and more particularly to a foundation unit which is amenable to storage and shipping in a collapsed state and later elevation to a fully expanded state using the available components of the foundation unit.
Foundation units are found in many forms. The typical "box spring" is composed of a flat wooden bottom frame, a grid wire top surface, and a series of transverse rows and longitudinal columns of coil springs attached between the grid wire and the wooden frame. Top padding and a cover is then applied by the manufacturer as required.
An alternative form for the box spring foundation unit is found in the applicant's U.S. Pat. No. 4,074,372 entitled "Foundation Unit Frame". In that invention, the applicant has disclosed a wooden frame of substantially greater depth, which increases the strength of the foundation unit, reduces the cost of fabrication of the foundation unit, and reduces the depth of the coil springs required.
Other, less expensive foundation units are fabricated using only a wooden or rigid wire frame. A build up of one or more inches of padding material, such as foam rubber, is used to cushion the top of the foundation unit for comfort.
A substantial disadvantage of all prior art foundation units is the requirement that the foundation units be stored or shipped in a fully assembled form. If not, substantial assembling must be done after shipment. In either case, costs are increased due to the large volume occupied by the foundation unit, or due to the large assembly costs after shipping if the unit is shipped in a knocked-down form.